This invention relates to improvements in a floor selector system for an elevator system.
In the operation of an elevator system it is indespensable to sense the position of the elevator car. This sensing is accomplished by an associated floor selector. A positional signal for the car delivered from the floor selector is used to display the position of the car on associated floors and in the car, and to determine if the car is to be stopped and so on. The floor displaying the position of the car is called hereinafter a "car floor" and the positional signal for the car is called hereinafter a "car-floor signal." There have been already employed various types of floor selectors. One of the known floor selectors has comprised an electric reversible motor, a screw rod connected to the motor to be rotated thereby, a movable nut screw threaded onto the screw rod against rotational movement, and a plurality of sets of position contacts, one for each floor of a building, selectively engageable by the movable nut during its movement along the screw rod. The floor selector has been arranged so that, during the ascent of the elevator car, for example, a car-floor signal is delivered each time the car passes through a predetermined point located above each floor. The car-floor signal is operated to rotate the motor to move upwardly the movable nut along the screw nut resulting in the closure of the position contact set corresponding to the next succeeding floor in the direction of the ascent of the elevator car. This closure of the position contact set delivers a car-floor signal which, in turn, stops the motor and also senses in synchronization with the movement of the car a synchronized floor corresponding to the now closed contact set. The process as described above is repeated to cause the movable nut to ascend stepwise with increments of one floor.
In the descent of the elevator car the movable nut is arranged to descend similarly with increments of one floor.
On the other hand, upon the start of the elevator car from each floor, an associated circuit has sensed therein an advanced car position or an advanced floor which is, for example, the next succeeding floor in the direction of travel of the car, in order to look for a call. In the presence of a call registered on that floor or a call for that floor registered on the elevator car, a command landing signal is delivered to cause the car to land at the floor where the call has been registered. Otherwise, the movable nut closes the position contact set corresponding to that floor having no call registered thereon whereupon the abovementioned advanced floor proceeds to the last-mentioned floor.
If the elevator car is suddenly stopped before it reaches that floor corresponding to the advanced car position then the synchronized floor is spaced from the advanced floor by one floor because the advanced floor is set upon the start of the elevator car. When the car is then started, the advanced floor is again set so that the synchronized floor is spaced from the new advanced floor by two floors. Under these circumstances, it is impossible to operate the elevator car smoothly.
In order to correct this spacing between the synchronized and advanced floors, the advanced floor must be returned back to the synchronized floor with a complicated circuit configuration. Furthermore, the floor selector as described above has encountered problems such as abrasion of the components involved because it relies upon mechanical operation and also increased manufacturing cost because of the use of the reversible motor which is expensive. There is therefore a demand for a floor selector which is highly reliable and economical.
Accordingly, it is an object of the present invention to provide a new and improved floor selector system for an elevator system for preventing a spacing between a synchronized floor and an associated advanced floor from changing even upon the sudden stoppage of an elevator car involved.